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bedrock was five feet in claystone and six feet in sandstone. The key depths were designed <br />based on design level seepage analyses. <br />More sandstone was encountered than was originally anticipated. Sandstones (or <br />interbedded claystones and sandstones) requiring a six feet key were encountered in the <br />following intervals: <br />• 0 +00 to 0 +60, <br />• 1 +00 to 3 +30, <br />• 66 +50 to 67 +90, <br />• 72 +40 to 77 +10, <br />• 82 +00 to 83 +70, <br />• 87 +60 to 87 +80, <br />• 91 +20 to 94 +70, <br />• 95 +10 to 101 +70. <br />Refusal was not encountered and full depths of key were execavated. <br />5.0 CONCLUSIONS AND RECOMMENDATIONS <br />Slurry wall construction was completed after 58 days of work. The construction was in <br />accordance with the plans, specifications, and quality control requirements. Full -time <br />monitoring of construction operations and testing of slurry wall materials allowed for <br />quick action in remedying problems. <br />Pumping from the previously mined area on the north side of the mine indicates that the <br />mine has drawn down well and does not appear to be leaking excessively. As mining <br />continues, Aggregate Industries should monitor pumping rates from the mine. Using the <br />area within the mine and the curtain area of the wall, it appears that the design leak test <br />standard is approximately 97 gallons per minute. If, after reaching steady state dewatering <br />Al finds that pumping exceeds this rate or if Al encounters areas that seep excessively, <br />Tetra Tech should be contacted for remedial options. Ultimately a leak test will be required <br />to demonstrate that the pit meets the seepage requirements of the State Engineer. <br />- 6 - August 2013 <br />P:\23514\ 133 - 23514- 13003\Docs\Repoits\ W attenberg _Constmction_Report_2013.doc <br />